The effect of oxybutynin on structural changes of the obstructed guinea pig bladder

Effects of oxybutynin in children with posterior urethral valves post fulguration: Report in a select cohort of children

Objectives:

Posterior urethral valves (PUV) is the commonest obstructive uropathy with varied consequences. Though valve fulguration is the treatment of choice, appropriate bladder management modifies outcome and includes rational use of anticholinergics. Here, we aim to evaluate the effects of oxybutynin on the bladder and urinary tract morphology and function. Concurrently, we document adverse effects encountered, patient compliance, and medication adherence.

Methods:

A retrospective study of children below 5 years of age (2012–2017) post fulguration and on oxybutynin for at least 6 months. Patient demographics, clinical features, renal ultrasound, micturating cystourethrogram, dimercaptosuccinic acid scan, adverse effects, and pill count for medication adherence were collated.

Results:

48 children below the age of 5 years were included, and 12 were excluded either due to the presence of concomitant problems or were not on oxybutynin. Of the 36, four were lost to follow-up and one had died due to an unrelated condition. Thus, a total of 31 children were analyzed. At follow-up, 28/31 patients were asymptomatic, two had daytime incontinence, and one had recurrent urinary tract infection. All patients except one have preserved renal function tests. On ultrasonography, hydroureteronephrosis worsened in only 1/25 children and two showed significant post void residues. The resolution of vesicoureteral reflux was noted in almost 50%. 4/31 renal units had progressive scars. Only two parents defaulted medication. Urodynamic study done in half of these children showed stable bladder pressures except in two.

Conclusion:

Oxybutynin therapy following adequate valve fulguration aids upper tracts preservation by stabilizing deranged bladder dynamics. The medication is well tolerated with minimal or no side effects.

Bladder attack: transient bladder ischemia leads to a reversible decrease in detrusor compliance

Background

The deleterious effects of chronic ischemia on bladder function have been extensively studied; however, evaluation and characterization of the effects of acute ischemia and hypoxia are lacking. The present study examined pig and human detrusor smooth muscle (DSM) strips, in combination with an isolated perfused working pig bladder model to evaluate the relationship between transient ischemia and bladder function.

Methods

Organ bath and myographic studies were performed using pig and human DSM strips exposed to starvation/hypoxia conditions. Analogous conditions were then recreated in the ex vivo bladder preparation. Filled bladders were then treated with intravascular carbachol to induce contraction and subsequent void. An intravesical transducer continuously monitored changes in bladder pressure, while a tissue pO₂ monitor analyzed changes in oxygenation.

Results

After 120 min in starved/hypoxic conditions, both pig and human DSM strips demonstrated significantly increased resting tone, with a greater than two-fold increase in force over control. This was effectively blocked with atropine. DSM strips also demonstrated significantly weaker contractions; however, contractile force was nearly recovered following 15-min exposure to replete/oxygenated buffer. In the ex vivo bladder preparation, filling under ischemic conditions yielded a 225% increase in end-fill vesical pressures (P_ves) compared to controls. End-fill P_ves returned to baseline with reperfusion during a subsequent filling cycle.

Conclusions

Transient ischemia/hypoxia leads to an acute increase in tone in both DSM strips and ex vivo pig bladder. Remarkably, the effect is reversible with re-perfusion and may be blocked with anticholinergics, suggesting a relationship between acute ischemia and increased local acetylcholine release.

Consensus on the Management of Posterior Urethral Valves from Antenatal Period to Puberty

The need for successful management of posterior urethral valves always captivates the minds of pediatric surgeons. Its success, however, depends on several factors ranging from prenatal preservation of upper tracts to postoperative pharmacological compliance. Regardless of measures available, some cases do not respond and progress to end stage. The management depends on several issues ranging from age and severity at presentation to long-term follow-up and prevention of secondary renal damage and managing valve bladder syndrome. This article is based on a consensus to the set of questionnaires, prepared by research section of Indian Association of Paediatric Surgeons and discussed by experienced pediatric surgeons based in different institutions in the country. Standard operating procedures for conducting a voiding cystourethrogram and cystoscopy were formulated. Age-wise contrast dosage was calculated for ready reference. Current evidence from literature was also reviewed and included to complete the topic.

Expression and function of the small-conductance Ca2+-activated K+ channel is decreased in urinary bladder smooth muscle cells from female guinea pig with partial bladder outlet obstruction

PURPOSE

Overactive bladder (OAB), usually accompanied by partial bladder outlet obstruction (PBOO), is associated with detrusor overactivity (DO) which is related to the increased urinary bladder smooth muscle (UBSM) cells excitability. Small-conductance Ca²⁺-activated K⁺ (SK) channels play a constitutive regulatory role of UBSM excitability and contractility. PBOO is associated with the decreased SK channels mRNA expression and the attenuated regulative effect of SK channels on UBSM contractility. However, the regulation of SK channels in PBOO UBSM cell excitability is less clear. Here, we tested the hypothesis that PBOO is associated with decreased expression and function of SK channels in UBSM cells and that SK channels are a potential target for the treatment of OAB.

METHODS

Cystometry indicated that DO was achieved 2 weeks after PBOO in female guinea pigs. Using this animal model, we conducted single-cell quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and patch-clamp electrophysiology.

RESULTS

The single-cell qRT-PCR experiments indicated the reduced SK channel mRNA expression in PBOO UBSM cells. Patch-clamp studies revealed that NS309 had a diminished effect on resting membrane potential hyperpolarization via the activation of SK channels in PBOO UBSM cells. Moreover, attenuated whole-cell SK channel currents were demonstrated in PBOO UBSM cells.

CONCLUSIONS

The attenuated expression and function of SK channels, which results in the increased UBSM cells excitability and contributes to DO, was discovered in PBOO UBSM cells, suggesting that SK channels might be potential therapeutic targets for the control of OAB.

Influence of sildenafil on blood oxygen saturation of the obstructed bladder

Background

Blood oxygen saturation (BOS) is decreased in a low-compliant, overactive obstructed bladder. The objective of this study is to determine the effect of Sildenafil (SC) on bladder function and BOS) in an in vivo animal model of bladder outlet obstruction.

Methods

Thirty-two guinea pigs; sham operated (n = 8), sham operated + SC (n = 8), urethrally obstructed (n = 8) and urethrally obstructed + SC (n = 8) were studied during an 8 week period. BOS of the bladder wall was measured by differential path-length spectroscopy (DPS) before obstruction, at day 0, and at week 8. The bladder function was evaluated by urodynamic studies every week.

Results

Before surgery and after sham operation all study parameters were comparable. After sham operation, bladder function and BOS did not change. In the obstructed group the urodynamic parameters were deteriorated and BOS was decreased. In the group obstruction + SC, bladder compliance remained normal and overactivity occurred only sporadic. BOS remained unchanged compared to the sham group and was significantly higher compared to the obstruction group.

Conclusions

In an obstructed bladder the loss of bladder function is accompanied by a significant decrease in BOS. Treatment of obstructed bladders with SC yields a situation of high saturation, high bladder compliance and almost no overactivity. Maintaining the microcirculation of the bladder wall might result in better bladder performance without significant loss of bladder function. Measurement of BOS and interventions focussing on tissue microcirculation may have a place in the evaluation / treatment of various bladder dysfunctions.

Identification of pathology from diesel exhaust particles in the bladder in a rat model by aspiration of particles from the pharynx

To determine whether diesel exhaust particles (DEPs) could be a toxic agent to the bladder, rats were exposed to different concentrations of DEPs for one month or three months. When the rats were sacrificed, morphologic changes of the urothelium were investigated. The antioxidase activity and the levels of lipid peroxidation in the bladder were assayed. In the three-month group, DEPs at doses of 21.03 μg/μl insulted the structural integrity of surface glycosaminoglycans, widened the gap between urothelial cells, increased levels of lipid peroxidation, and decreased antioxidase activities in the urinary bladder (p<0.05). Furthermore, DEPs at a dose of 5.61 μg/μl decreased glutathione, catalase, and glutathione peroxidase activities (p<0.05). These results led to the conclusion that DEPs were a toxic agent in the bladder. The toxic effects might be attributed to oxidative damage mediated by pro-oxidant/antioxidant imbalance or excessive free radicals.

In vivo measurement of bladder wall oxygen saturation using optical spectroscopy

Current diagnosis, follow-up and treatment of patients suffering from bladder dysfunction are mainly symptom-targeted. A recently recognized cause of continuing bladder function loss is a deteriorated bladder microvasculature. Incorporating this aspect into the clinical diagnostic toolbox may improve treatment results. Recent developments in the field of optical spectroscopy now allow for non-invasive measurement of microvascular blood oxygen saturation in living tissue. We have recently reported pre-clinical data that show that this marker can be successfully measured in an animal bladder. In the animal model the marker differentiated bladders with loss of function from those with normal function. In the present paper, we report on the first in vivo measurement of this marker in the human bladder, as proof of principle, in the muscle of bladders with a normal function.

Changes in bladder wall blood oxygen saturation in the overactive obstructed bladder

PURPOSE

Several studies suggest that hypoxia of the bladder wall contributes to bladder dysfunction but the exact relation between bladder function and blood oxygen saturation, a surrogate marker for hypoxia, is not known. We determined bladder wall blood oxygen saturation in vivo in an animal model of bladder outlet obstruction to establish the exact relation between blood oxygen saturation and bladder function.

MATERIALS AND METHODS

In 8 sham operated and 8 urethrally obstructed guinea pigs we measured blood oxygen saturation of the bladder wall by differential path length spectroscopy before surgery and 8 weeks postoperatively. Urodynamic investigations performed during the whole 8-week period provided data on bladder function.

RESULTS

Before surgery and 8 weeks after sham surgery blood oxygen saturation in the bladder wall was between 88% and 95% during filling. It decreased during voiding and returned to greater than 90% within 30 seconds. Eight weeks after obstruction saturation was significantly lower than in the sham operated group during filling and voiding. The decrease was positively related to bladder pressure during filling and voiding, and was more pronounced when overactivity was present. Local bladder contractions occurred without a measurable increase in bladder pressure but were associated with a decrease in saturation.

CONCLUSIONS

A normal bladder maintains a high oxygen saturation level during filling. Bladder obstruction compromises this ability, especially when it involves overactivity. Local bladder contractions without a measurable increase in bladder pressure were associated with a decrease in blood saturation.

Intravesical oxybutynin in the pediatric neurogenic bladder

Pediatric neuropathic bladder dysfunction can cause irreversible renal damage and urinary incontinence. Etiologically, it is usually the consequence of a congenital neural tube defect. The majority of affected children can be successfully managed with the standard medical treatment of clean intermittent catheterization and anticholinergic (typically oxybutynin) medication. A subset of patients experience severe side effects or insufficient suppression of detrusor overactivity on oral oxybutynin. Intravesical instillations offer an effective alternative; this Review considers their indications, administration, safety and efficacy.